MRI helps detect sports-related knee, ankle injuries

Using MRI and radiographic imaging, researchers found a new indirect sign of syndesmotic tears or high ankle sprains.

Magnetic resonance imaging can help identify and diagnose serious sports-related knee and ankle injuries, according to two studies by Pennsylvania researchers.

Jeffrey Towers, MD, an associate professor of radiology at the University of Pittsburgh Medical Center, and colleagues reviewed 101 knee magnetic resonance imaging (MRI) exams of 330 candidates for the 2005 National Football League (NFL) draft. They found 57 lateral meniscus tears and 26 medial meniscus tears.

The researchers initially suspected that the lateral meniscal tears were associated with ACL tears, as 80% of meniscal tears occur in association with ACL tears. Yet, just 18 lateral and eight medial meniscal tears occurred in conjunction with ACL tears. Of the remaining knees, 36 lateral and 18 medial meniscal tears occurred as isolated injuries, and three knees showed evidence of prior lateral tears, according to the study.

“These findings are remarkable because the authors of most previous studies have reported a predominance of medial meniscal injuries,” Towers, who presented the results at the annual meeting of the Radiological Society of North America, said in a press release announcing the results.

“The fact that we found a concentration of lateral meniscal tears could mean that there’s something about this sport (football) that predisposes athletes to this injury,” Towers said. “We found the highest incidence of lateral meniscal tears in linemen and defensive secondary players. Now that we recognize this, there may be ways to address the players who are most at risk for this injury.”

Radiograph showing posterior malleolar anterior capsular periosteal new bone.	MRI showing posterior periostitis.
COURTESY THE RADIOLOGICAL SOCIETY OF NORTH AMERICA

High ankle sprain

Towers and colleagues also conducted a second study involving candidates for the 2005 NFL draft. Using MRI and radiographic examinations, the researchers identified a new indirect sign of syndesmotic tears, more commonly known as high ankle sprains.

In syndesmotic tears, which are often misdiagnosed, the fibula can move away from the tibia and the cylindrical groove forming the ankle can widen under load. Physicians commonly diagnose the condition through physical exams of the syndesmosis.

“If it is not recognized, and you send somebody out to play, the ligaments heal improperly, the ankle doesn’t fit as tightly as it should, and often the result is arthritis,” Towers said.

“The problem is that routine x-rays may not show it, because it's not grossly misaligned. It’s during athletic activity when the injury becomes most apparent,” he said.

This second study involved 18 patients who had a history of high ankle sprain. On 14 radiographs, the researchers found evidence of abnormal new bone growth, or periostosis, at the lower part of the tibia. Two MRIs also revealed abnormal swelling from fluid at the same site.

“If I look at an ankle and see this posterior periostosis, I can now be fairly sure of a syndesmotic injury,” Towers said.

For more information:
Towers J, Armfield D, Buckwalter K, et al. Distribution of meniscal tears at MRI in elite football players. #SST16-01.
Towers J, Armfield D, Buckwalter K, et al. Posterior malleolar periosteal injuries in football players with high ankle sprains. #SST20-02. Both presented at the Radiological Society of North America. Nov. 26-Dec. 2, 2005. Chicago.